1. Field of the Invention
This invention relates to an apparatus for automatically delivering a workpiece and particularly to such an apparatus of the type in which a holder means for holding the workpiece is moved both horizontally and vertically through a single motor.
2. Prior Art
In the case where a workpiece is subjected to pressing operations at several stages to have a final shape, it is desirable from viewpoints of operator safety and operating efficiency that the workpiece is automatically delivered from one press to another by an automatic delivery apparatus. Most conventional delivery apparatuses have employed at least two different kinds of drive means such as a motor, a pneumatic actuator for moving a workpiece holder both horizontally and vertically. As a result, such conventional automatic delivery apparatuses are quite bulky. In addition, in order to carry out the horizontal and vertical movements of the workpiece holder in a smooth and continuous manner, such conventional delivery apparatuses have required a plurality of sensing means such as a limit switch for sensing the limit positions of the horizontal and vertical movements. Therefore, the conventional delivery apparatuses have frequently operated improperly because of such a complicated sensing arrangement.
Further, each time the strokes of the horizontal and vertical movements of the workpiece holder is to be valid, the positions of the plurality of sensing means must be adjusted. This requires much time.
Another conventional automatic workpiece delivery apparatus employs two pneumatic cylinders for carrying out the horizontal and vertical movements of the workpiece holder, respectively. This conventional delivery apparatus is also disadvantageous in that the switching of the horizontal to vertical movements, and vice versa is rather difficult to be carried out, so that many expensive control parts are required to effect the horizontal and vertical movements in a smooth and continuous manner.
A further known automatic delivery apparatus employs a single motor for carrying out the horizontal and vertical movements of the workpiece holder. Two clutch mechanisms are provided in a power transmission line of the motor for controlling the horizontal and vertical movements of the workpiece holder. Thus, this conventional delivery apparatus is complicated in construction and therefore susceptible to malfunction.